Field of the Disclosure
The present invention relates to a preformed insulation structure for a transformer, a transformer comprising a preformed insulation structure, and a method for producing a transformer utilizing a preformed insulation structure. Such devices are used in isolating transformers, for example, in which high voltages are present between a primary winding and a secondary winding.
Background
Transformers, and in particular isolating transformers, can comprise a transformer core and at least two windings. In some isolating transformers, the windings are wound in a bifilar arrangement. One exemplary bifilar arrangement is shown in FIG. 1. Two windings 102, 103, formed with wires, are wound around a ring-shaped transformer core 101 in a plurality of turns. In one example, both windings 102, 103 may wrap substantially along the entire circumference of the ring-shaped transformer core 101 in order to limit leakage inductances. In this arrangement, the insulation resistance between the first winding 102 and the second winding 103 is substantially determined by the insulation resistances of the wires which form the windings. In order to maintain electrical insulation at high voltages, for example voltages between 1 kV and 25 kV, the thickness of the insulation material of the wires can generally be increased. However, increasing the thickness of the insulation material of the wires may increase the overall volume of the windings 102, 103. To maintain the same turns ratio between windings 102, 103 with wires which have a thicker insulating material, a larger transformer core may be used. As such, the overall size of the transformer may increase.
In other examples, the two windings of a transformer can each be wound along their own respective segment on the circumference of a ring-shaped transformer core (for example along a 120° segment). A distance between the first and second windings can thus be increased. However, as a result of this arrangement of the first and second windings, the leakage inductance of the windings can increase and likewise result in an increased sizing of the transformer core and of the entire transformer, as a portion of the transformer core is not used for winding the windings.